Area Forecast Discussion
Issued by NWS Spokane, WA

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000
FXUS66 KOTX 190014
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
514 PM PDT Thu Apr 18 2019

.SYNOPSIS...
Numerous showers and an increase in westerly winds is expected
Friday. There is also a chance of thunderstorms in the afternoon
across extreme eastern WA and the ID Panhandle. This weekend and
much of next week will be dry with seasonal temperatures.

&&

.DISCUSSION...
Tonight through Friday: An amplified upper level ridge is
bringing fair weather across much of the Western US. The ridge
axis has now shifted eastward into Montana. Moisture has been
spilling over the top of the ridge, bringing light rain showers
along the Canadian border, with light sprinkles reported as far
south as the I90 corridor. This band of precipitation is showing
signs of weakening as it nudges against the upstream ridge.
Extensive cloud cover this morning along with the precipitation
has kept temperatures a bit more suppressed than originally
thought. That being said, widespread 60s are still likely by late
this afternoon across the lowlands, with 70s for portions of the
Columbia Basin eastward toward the Lewis-Clark Valley.

Our attention then moves toward our next weather system,
currently off the PacNW coast. This system has been trending
weaker and slower the last few model runs. While a few showers
will continue to be possible near Canada through tonight, the main
front is now expected to move through the region around midday
Friday, with precipitation mainly favoring the higher Cascades,
far eastern Washington, and northern Idaho. Precipitation will
likely be convective in nature, and a couple thunderstorms cannot
be ruled out. The best chance of thunderstorms will likely be
along NE Oregon into central Idaho, where some of the Hi-Res
models are hinting at substantial rain rates. Will need to monitor
this area closely for the potential for rapid rises in river and
streams.

Winds will likely increase as well across the lowlands. Pressure
gradients aren`t expected to be as strong as previous forecast,
but southwest wind gusts of 20-30 mph appear likely. This could
impact outdoor recreational activities during the holiday weekend.
Dang

Saturday through Tuesday...A dry northwest flow will be over the region
for Saturday as high pressure builds in from the west behind the exiting
storm system on Friday. Lingering moisture will keep a mention of showers
in the forecast for Shoshone county south to the Camas Prairie and the
Blue mountains. Precipitation amounts will be quite light with just a few
hundredths expected. Snow levels will be above 5000 feet or more so snow
is expected only at the higher elevations. A flat ridge of high pressure
will then dominate the weather pattern through Tuesday. Model guidance is
quite variable showing that perhaps a couple of weak waves could move through
southern B.C. on Monday. If they do it would result in some light showers for
the northern mountains. Otherwise conditions will remain dry with afternoon
high temperatures in the low 60s to mid 70s and overnight lows in the mid 30s
to mid 40s. These temperatures will be 3-6 degrees above average. Warmer
temperatures will allow for continued snow melt. Area rivers and streams
will be running seasonally high but all are expected to remain well below flood.

Tuesday afternoon through Thursday...Model guidance through the extended period
is quite variable and this forecast leaned in favor of ensemble forecasts. That
is the jet will sag south as a series of weak Pacific storms will move through
the Pac NW. As the jet migrates south these the chances for measurable
precipitation will increase. Confidence is good that we will see cooling trend
and wetter weather. However, confidence in the timing of any given storm is
still suspect. Tobin

&&

.AVIATION...
00z TAFS: VFR conditions will prevail through the period. Mid and high clouds
will span across the northern Washington and far northern Idaho. This cloud
deck will sag southward on Friday as a cold front sweeps through the region.
Expect gusty west to southwest winds after 18z with light showers possible from
KGEG-KCOE. Showers will develop near KLWS after 21z with locally heavy rainfall.
Late Friday afternoon, there is a small chance of thunderstorms both north of the
KGEG-KCOE corridor and south of KLWS although confidence on location is
low. /rfox.

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        50  65  42  61  36  63 /  10  50  20  10   0   0
Coeur d`Alene  49  64  41  60  36  64 /  10  70  40  10   0   0
Pullman        49  66  43  57  36  60 /   0  50  50  10   0   0
Lewiston       54  73  50  63  43  66 /   0  60  60  20   0   0
Colville       46  69  36  68  31  72 /  20  50  20   0   0   0
Sandpoint      48  60  40  60  36  63 /  30  80  50  10   0   0
Kellogg        49  63  42  58  37  61 /  10  70  60  20  10   0
Moses Lake     52  70  44  68  40  70 /   0  20  10  10   0   0
Wenatchee      52  66  42  65  41  68 /  20  30   0   0   0   0
Omak           49  68  40  65  38  68 /  20  30  10   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.

&&

$$


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